Glazing bar



Jan. 22, 1935., R. w. EMERSON ET AL 1,988,647

GLAZING BAR Original Filed April 5, 1931 3 Sheets-Sheet l Aw lg JZ @.9

Jn. 22, 1935. R. w. EMERSON ET AL GLAZING BAR Original Filed April 3,1931 3 Sheets-Sheet l2 waff/Waver' I @VEN/2:71475 I ,@@Z @Emerso w Jan-22, 1935. R, `w. EMERSON Er Al. 1,988,647

GLAZING BAR Original Filed April 5, 1931 3 Sheets-Sheet 3 Patented Jan.22, 1935 uNlrli-o STATE 1,938,644'11-7 t "cLnziNGisAn ,y n Ralph W.Emerson, Y Chicago, and f Stirling." if

PAT

Harper, Wilmette, Ill.:- f Y 'Application April a, 1931,'seriai'ivdismso -V VRenewecrl June 14,v 1934 V 5 Claims.'l (m5108515)2.3.

'Ihe present invention relates .to'glazing bars for buildings and hasparticular. reference to glazing bars .of extruded aluminum.`

An objectV of thepresent invention-is to provide glazing bars ofaluminum. v

A primary object .ol the present invention 'is to provide a new methodof securing glass or other.v

sheet material to glazingv or'other framing bars of structures or partsof structures built of metal or wood bars and sheet material, andfurther toy tioned deteriorationof"materials, leakage of.

weather from without and water of condensation from within,uncontrollable air leakage, excessive breakage of glass due to localizedfixed or screwed fastenings, the difficulty of replacing sheet material,and the high cost of both construction and;

maintenance.

To provide against deterioration of materials and to aid in reducingthe. manufacturing cost the metal parts of the present invention aredesigned to be made from' aluminum or if desired from bronze or othernon-deteriorating metals, by

rolling, die drawing, stamping, extruding or other similar methodswhereby low cost of production in large fvolumes of accurately formedespecially designed parts is secured.

There is everywhere a growing demand for light weight simply andeconomically constructed enclosing wallsland roofs, which, occupying aminimum of space, are still so designed and constructed as to overcomeall previous diiculties and be attractive and clean. in appearance withthey design of the various parts expressing the function of the same.The constructional features of such parts must be adapted either toglazing or to closingin with thin sheet material.

Where glazed such structures must oler the minimum of obstruction tolight from various directions. n

' Structures towhich the typeof the construe'- tion` of the presentinvention might-be applied are generally built with a skeleton framework"formedg .n

of.. which the supporting. members for .the hereof the present inventionwould `betl'ie. purlins otr roofs or walls'or the wall mandrel'beams..Yl Another. and still vfurther .obiectotrthe inven-Y. tion is to providemetallic glazing barszandnovel anchoring means fori securing.said-.barstoi .the. frame structure .mithout'zthe fuseoi;rivets,kfbolts, or like fastening. means....l.fv.. f y .f g... j

The new vmethodoi the V.present invention for securing glass orv other..sheet material Vto glazing' or framing barssfconsists primarily'in-:.theguse of preformed springcoversso de'signedoof. ;springymaterial whereby the covers may .bereaslly snapped over or easily.removed atiwllfrcmsuitably formed .and cooperating-headed glazing., or.framing bars and t to retain :thecovers LinFene-lf: gagementV witl'i-1vsaid`v bars Lwitlrtcontinuous spring pressure thus holding. the.covers:inrpositioxil I'The i coversof .the present invention. are `notcrimped or bent buty rely for the spring actionaduefto the construction.of the coverspfor retaining thofs'ame in applied positions. ,1 Theabove, other, and furthennbiects; ofgthe invention will be apparentirom.the.-folloiivi'nsf` description, accompanying. drawingapand appended.

claims. Embodiments of the invention mare illustrated in .theAaccompanying drawinga and the views". thereof are as follows?. 1"-

; Figure.I 1 is any isometric view of-.abar madein accordancewitlrf-thev present invention showing the section ofthe bar.:V .1112;Figurezisa fragmental enlarged partialL sectional view showingone meansfor securing-glaz.-V ing bars 'of the. present invention tothe buildingl structure;` and also one meansvfor supporting cross glazing bars. l

4 Figure ais an enlarged vertical transverse *sec-.

tional view taken throughl abar such as' that of Figurefl showingthesamezinstalled in afmild` ingand the preferred vmanner of supportingthe? glass.-r L..

Figure 'lisa fragmental isometricview'of a modied form of bar with aglass ledge and gutterV on bu't'one sident the same. .r f 1'. `Figure y5is'. an enlarged y:fraziriental sectional viewshowing the glazing bar.ofthe present-in,N vention' as :the same appears when mounted along atruss adjacent theiunction fof that truss with a y trussfcrminga-purlin... 1 1 4 Figure 6 is afrasmentel isometric view of a barof modied section..r. ..1 l Figure 'l 'issn-isometric view cfa combinedglazing bar andra'fter entraine memberintecrally with any type ofbuilding or roof construction,"l Y,

movement of the clip with respect to such bar. The length of the portion13 is such that the inner surface of the end member and also of the bodyof the clip bears against the adjacent upturned edge 4 and cannot bedriven against such upturned edge with suiiicient force to distort orbreak the same. Two clips B are generally utilized to secure one of thebarsA toga purlin-between trusses or rafters.. -The two vclips soemployed are secured together by a bolt 14 passing through suitablydisposed apertures in the clips which bolt is fastened by means of a nut15.

steel, wood, or otherwise wherein the rafters-"or -"-"'When the glazingbars A are extruded a groove trusses are connected` atIairiteryrallsby4.purlinsg` preferably of channel or angle membersg; The roof bars orglazingnbarsdare arranged along the rafters or trusses runningfromthe'"peakl` of the roof down to the sides of the building' or likestructure and also disposed at intervals;lzietvveerl` the trusses orrafters or purlns which run lengthwiser'ofthe.buildinga-iifl'heglazingbars may extendtofthe ground tli'nelifydesiredn ix The glazingzbarsillustratedin Figures 1, '3,15 and: 8'aremade'o'eXtI-uded aluminum: forming bulbous headsilv, webs2;bottomilan'ges-lw'ith in-f clined side:marginsif'andiledgest 5intermediate 1 theheads'and'thefbottomflanges.u11kt-v` f a The ledges 5are formedifoneachr'sdexoffthe webs 2except ini-.such instancesrwhere itis-'desired to supportglassfpanesalongone sideonlyof vsuch Ibarsirrwhich eventi-theilbas'e and' ledge onone=side .ofthe webstareomittedas illustrated iniFigurezl, 'z i The .uptuedl side -r-narginsf4 v4cooperate with;

thecwebs ..2'; #."Preferablyrthe 'upper'. :faces .of Vthe ledges-5 arecorrugated -to retainithe bed gzfor: the glass :panesfon'theledges.=f'`rr fy .'Thebar as illustrated in Figures 1,23; 5,.;and 8is so. fashioned'as'.t distribute. the metal sym.

metrically about v:vertical'andA horizontal axes of the section of thebar thus aifording suiiicient strength'and1rigidity.-f 2 :1:15 l ai,

V'I'l:ie:'barillustrated'in Figure 1fis` full size and is thesizeactually used as glazing: bars for .buildmgs. :.-r

rThe rafters .orfitrussesf' may be fofraanyxdesi'gn whatsoever and of 1wood; steel, or.v other material-.i Figure 5 illustrates a glazingeba-rA' secured' along' a'trussT formedsin the `presentinstancev with angles6and'l'7 andanintervening plate 52.0n the upper edges of which the bar-Arests.: a 1 f 'At intervals'inv the'lengthof .the truss. orrafter formedby the angles 6 fandw'ljpurlins 8 .are fas-V tened lin: anyl'desi-red'.manner such fortinstance, byangleplates: at thelconnections.The-purlns run lengthwise of the building or likefstructure;l that is,perpendicularly to` thetrussesor rafters.'

The' 'glazing' :bars TA.- fastened .to 'the-'purlns'. 8 intermediatethel lraftersfor. -trussesvare secured' thereto'lby-clips asillustrated'inFiguresjlZand 3-.' Each clip B comprises a body 9 havingan rend, 10 spaced from-the `body at. ,one'-.end.th"ereofi and ashoulder-11 'at' the'lother end. The end-ljex-.z tends inwardly from theadjacent. end:V of? :zthe body B rand2 disposed-ite "underlie the'.'upper flangellzsof apui'lin 8'.: `The clips'rB 'areffastenedY to' theflanges. 12: of lthe..-purlins: 8 y by-hooking' the end 10 yunder the4under surface'fof the; upper flange 1 and snapping the shoulder'llivdownf over the web 'of' the 'purlim .y The'clip :Bs is' preferably ,ofspring metal and forms tight-eonnectionawithlthe puninsQ-f jrneenpiisfprovided-iwan inwardly directed' portion 113 f-forb'earing'againstAth'efradjal cent face of the web ofthe bar Ato limit inward f 17 isformed in'each side of the web 2 beneath the .v1edgev5 as a drillcentering groove so that the web maybe drilled wherever it is desired toinstall lclips-"Bandthe boltsA 14. The grooves 17 serve to center thedrill point while making such bolt holes.

The arrangement shown in Figure 3 is that looking at the left side ofFigure 2 and is somewhatenlarged."

Figure 3 illustrates one manner of "supporting glass'panes C by theglazing bars ofvthepresent invention. A strip of plastic material 18 islaid along the ledge 5' on veach side ofthe web 2 of the bar andanother'strip 19 of plastic material is laid against the web2 adjacentthe ledgesv 5. The

panes Care then placedon top of vthe plastic strips 18 whereupon plasticstrips 20 are laid along have the lower portions outturned forming seats22 and2l for bearing against the sheet material suchas glass which is tobe maintained' in proper' relationwith respect to the framing bars A.The undercut grooves 23 yreceive the legs 24 of the cl-ips or'covers Dwith the grooves serving. as a continuous fulcrum to transmit a portionof the internal spring action of the curved part 54 which acts to 'bendthe legs 24 towards each other and thus hold the cover onto the bar withspring action. yThe "topf'54 of thecover, when'the cover in appliedposition, i'sout of contact with the bar -A thus providing an insulatingspace between the cover'and the' bar. The 'form of the seat or flangesQland 22 is vsuch .that any resultant of outward force exerted on thesheetmaterial combined with the -forces created vby the. internalspringaction-of the -legsV 24 and the top 54` serves? ends of the,covers to insure continuously uni form retaining pressure Aagainst thesheet ma,A

ter ial..,' v 5 ,Y Y y Preferably the spring `covers D are made inlengths equal to the lengths ofthe sheet mate# rial B with slightlydeformed overlapping lportions at the y ends of the cover to insurelcontinuously uniform' Ypressure Aagainsttthe sheet mate-,- rialforretaining it in DQStion.f

of length of cover on 'either side isthusv required to be only onetwenty-fourth Yof the amount off pressure which would berequired wereretaining fastenings spaced twenty-four inches apart. It is by thisimprovement that is re'ductin` of the unit pressure and continuity ofuniform pressure that the present invention eliminates breakage of sheetmaterial. 7 I

Assisting in the elimination of breakage of the sheet material such asglass is the use of the cushioning or bedding strips 20 interposed alongthe margins of the glass sheets where the same are supported in theframe structure, and the choice of the preferred metal, aluminum, whichhas mechanical properties substantially the same as of glass.

The covers D are easily applied over the heads of the supporting bars bypressure applied along the tops 54 of the covers and may be easily re.-moved for replacing broken glass or thev like by beginning at one end ofa cover and spreading the skirt or pressing the curved top 54 toward thehead of the bar thusfreeingthe engaging legs 24 from engagement with theundercut grooves 23 in the bars. I

No fastening means of any character are employed to maintain the coversin position as the spring pressure of the covers against the vbars issufficient to retain the same under all conditions of service.

The undersides of the heads 1` of the glazing bars are undercut as at 23to receive the inturnedv portions 24 of the clips D.

The glazing bar E of Figure 4 comprises a head la, a web 2a, a bottomflange 25, an upturned side marginal iiange 26, and a ledge 27. Thebottorn flange 25, side flange 26, and glass ledge 27 are formed on oneside only of the web 2a for' use where it is desired to support theglass along one side only of such glazing bar such forinstance asillustrated inl Figure 10.

A groove end of a clip D' for securing the clip to the bar. Figure 6illustrates an extruded aluminum glazing bar which is utilized to extendalong the roof in register with the purlins and consists of a top flange28, a web 29, a glass supporting ledge 30 on one side of the web andanother glass supporting ledge 31 on the opposite side of'theweb. Agutter 32 is formed by a portion 33 spaced below the ledges 30 and 31 onone side of the bar. This bar F is illustrated in Figures 2 and 10. Theheight of the bar F that is from the flange 28 to the lower surface ofthe lowerl portion 33 forming the gutter is less than the overall heightof the bars A and E. Figure 8 illustrates an assembly of a glazing bar Aand two glazing bars F. It will be noted that the lower portions 33 ofthe bars F rest on top ofthe side flanges 4 of the bar A thus spacingthe bars F above the truss o-r rafter carrying the glazing bars A. Inthis arrangement the gutters 32 of the glazing bars F discharge into thegutters formed in the bars A whereby condensation may be carried away toeavesor outside gutters as desired. In Figures 9 and 10 showingfragmental portions of a roof construction utilizing the glazing bars ofthe present invention a ridge 34 is supported on a separator plate 35suitably attached tothe roof framework. Glazing bars G are provided forcooperating with the separator'` plates 35 and the ridge 34. The ridge34 has converging portion 36, vertical portions 37 therebelow,

53 is cut in the headfla to receive an outturned'a'nges 38 'and-upwardlyinclined side flanges 39-.-Th portions 37and the flanges 38 andl9zformjng` gutters 40. The glazing .bars 6 are-suitablyi2secured to theinclined portions 36 and as shown are arranged in'back to back relation.

Each glazingbarGis provided with a laterally i extending i. lug- 42.toreceive panes of glass suitably seated thereon by plastic strips ofthe character and arrangementas described with reference to Figure 3.Clips 'Df cooperating with the heads 41 of the glazing bars G retain theglass panes against the'lugsorshelves 42 in the same manner asdescribedzwith .the preceding figures.

Theheads ,41; aregrooved'to receive the inturned portions 54 of theclips D;

' The portionv of roof illustrated in Figure 10 is inclined with.glazingbarsA extending along the rafters'or trussesfdownwardly from theridge 34. *Purlins 8 are provided on which similarglazing bars A- rest;`

Extending lengthwise of the roof, that is, parallel to the separatorplate and overlying the Vseveral purlins 8 are glazing bars F arrangedwith the'lo-wer portions 33 of the bars F above the,

upper flanges of the purlins 8.V Any condensation accumulating in thegutters 32 of the glazingibars F passesrinto `the gutters of the bars Aat the ends of the bars F so that such condensation may. pass downwardlyto suitable eavesA for disposalzY The glass Vpanes are supported vonthe: ledges or shelves 30 and 31 of the glazing bars Fbeing spacedr"therefrom by, plastic strips 43 with upstanding. strips against theadjacent edges of the panes. It will be observed that the upper edge ofthe=paneis inserted between the flange 28 and the ledge 30 so thataccess of rain, snow, and the like is prevented'whereas the lower marginof thepane is supported on the ledge 31. The provision ofthe plasticstrip 43 and the end strip 44 prevent seepage of rain and the like pastthe panes.

The clips D and Di cooperating with the glazing bars A may be made aslong as desired that is as longv as the several bars A so as to have noopening through the same. Although for convenience in replacing broken'panes of glassthe clips are made in length the distance from :onepurlin to the next as preferred.

The glazing `bars A, E, F, and G may be bent to provide a roof structureof any desired shape.

These bars `may be extruded at the mill and supplied in any standardlengths such as 8, 10, 12, 14, 2 0 feet and the like and cut to properlengths on the job. The bars may also be bent on the job to provide thecurvature desired.

Figure 5 illustrates one manner of tying glazing bars Awhen vthe sameare mounted alongthe ilar tohthe-y arm..10 offthe vclip lB villustratedin Figure 2. The clips .45 `are arranged. one. onv each side of aglazingbar A where the-'same is'disposed along the truss, or.rafter-jandare .held inv position bya bolt `50 passing throughZapertures in the clips and also in-thezweb 21of thebar A. i

It will be observed that the bars A are designedv so that median linesboth verticalandhorizontal are drawn through-*a-sectionvof the same,show an even dispositionof meta1'above`and`below and. 'also on eachsideofJ suchmedian lines.

and rafter .5l may also be bent. toprovide a roof of 'desired shape. 1 fr v It will be 'observed` thatthis-invention provides glazing bars whicharelight, strong-and. which are made of metalpwhichf is not subject-todeterioration by weatherconditions.Y -Such bars v.are

easily bent to provide. structuresgof anydesired. styleand shape andalso. are light enough to be` readily installed without excessive labor.The use of clipsfor attaching thesebars to the structureV is benencialinthat the vclipsmay be arranged along the length ofthe `bars as desiredand secured thereto in selected positionsv by', bolts .passing throughthe' webs of. the bars, the-.bolt holes being formed-at desired pointsbythe erectorwho'readily centers his drill in theldrill-notch providedfor this purpose. The clipsarespring clips whichY grip the purlinstightly to prevent displacement of the'glazing bars in service.

The use of glazing Ybars in 'the-present invention maybereadilyxunderstoodand also thead-z vantage' of the Abars .inthepresentinvention: may

be understood. 'Ihe bars-of this invention may be manufactured in anystandard lengths -asl desired, transported'to the place of use and therecut to proper lengths whatever-'the lengths may be` and also shaped to`propel-curvature thusV reducing the laborcostfincidental tothe erectionof greenhouses and; llike structures. .The glazing bars being ormetalare stronger than those made of wood and at the same timeare of muchsmaller cross sectional area so as to reduce to a minimum the shadow.eiect created by Ithe glazing bars.v

These bars being made-of aluminum s uier no ill effects from weather'conditionsand consequently do not have to be repaired or painted. l

Figure l. illustratesgfull size ofrthe bars of type- A whereupon itmaybe readily understood and observed that suchl-barsreduce tota.Vminimum the shadow effect created by reason of thepuse of the same.Ittwillwbe. observedalsov that bars of the type A. are much smallerthanyWooden bars would haveto be same size and area. f

y It may be readily `uriderstood that special'y shapes of thesebarsv'may bereadily extruded as The glazing' ba'rs `of :the ,present=invention can be usedto. supportthe glass panes'inan overfor supportingglass of,l the g. purposes. The use of spring clips for maintaining thepanes in position on the glazing strips serves at all times to wedge thepanes against the embedded mastic thus assuring a weatherproof joint atthe glazed portion.

The mastic which is proposed to be employed in glazing with the bars ofthe present invention is made up. in strips-or rolls so as to be readilyunrolled or set along a glazing ledge or shelf thus reducing costofapplicaton ofv such mastic and doingaway with the necessityA of usingputty as vmust be done with mastic or equivalent substances, in otherforms than rolled or in strips.

The. mastic. or embedding.. material utilized along the edges of theglass pane is preferably of an asphaltic compound with asbestos orsimilar iiber incorporated therein and is made in the manner ofIapreformed strip or tape of sectional contour conforming to theglazingbars and the spring cover of the invention. The tape is preferablysupplied to the job in roll form with a separating strip ofpaper`between the layers so that the tape may be unrolled along the marginsof the glass .or other Vsheetrnaterial employed to expedite theapplication of thetape to the material. The use of the bedding materialin tape form enhances-the appearance 'of the nished structure and notbeing necessarily vinjured in application or removal `may be reused ifoccasion arise.

The glass supporting ledges of the bars of the present invention areprovided with a multiplicity of grooves and projections 55 and 56respectively which cooperate withand retain in proper position themastic tapematerial. Y It has been found in practice that glasssupported ony steel bars breaks more readily than when supported onwood. The natural characteristicskof glass and aluminum are similar andless breakageof glass should occur with aluminum than with wood. Themodulus of elasticity of aluminum and glass is approximately the sameWhereas for steel itis three times that of glass or aluminum.v Y l j Thesize, shape and arrangement of the illustrated form of bars are designed-for strain where the bar is supported at intervals of ve to six fleet,thus doingaway with the intermediate support necessary when Wooden barsare employed. `'l'rhe protuberances 55are provided for thepurposeVof-urging the mastic downwardly against the pane when the clipsare applied to the bars,

for retaining the paneon the bars. n

. Theseparator plates 35 illustrated `in Figure 10 are usually shortplates disposed at intervals in the length of the ridge 34 and are withthe ridge.

n labor in the field and designed so that as much Work as possible mightbe done in the shop thus reducing the eld labor to avminimum.

All theerectors have to do in applying glazing bars vof the presentinvention is cut the same to proper' length which maybe readilydone witha hand saw, apply the clips for fastening the bars to the purlins ortrusses and drill the webs wherever any of the bolts'14 and l5 are tobe'inserted. The provision of the notches 17 in the webs of the barsserve as centering notches for the drill so that the erector does nothave to ascertain the correct place for the hole and use a prick punchfor indicating the place to be drilled. He ascertains the correctposition for the bolt and then places his drill in the groove and drillsa hole for the bolt. s

Referring to Figure 10 where the :bars F are shown as supported on theupturned flanges 4 of the bars A, it will be observed thatl the bars Fare illustrated in this manner for clarity of understanding whereas whenit comes to practical in-y stallation, the bars F are mounted on theclips 9 as illustrated in Figure 2. Mounting the bars F in the mannerillustrated in Figure 2, especially in a sloping roof the clips 9 serveto prevent movement of the bars F downwardly as it will be noted thesebars rest against shoulders formed in the clips thus preventinggravitational movement downwardly.

The clips of the present invention engage the sides of the glazing barswith uniform and continuous pinching action from Vend to end, withskirts or seats which rest against the sheet material, consequentlyyexerts continuous pressure against such sheets. This provision ofcontinuity of pressure along the sheet material prevents fractures andbreakage such as are found in clips or attaching means ofdiiferentconstruction.

The invention has been described herein more or less precisely as todetails yet it is to be understood that the invention is not to belimited thereby as changes may be made in the arrangements andproportions of parts and equivalents may be substituted withoutdeparting from the spirit and scope of the invention. v

The invention is claimed as follows:

l. Means for securing sheet material such as glass to framing or glazingbars, said means comprising spring sheet metal covers of uniform sectionand having substantially arcuate circular central portions with thesides thereof inturned and then down and outturned, the inturnedportions constituting engaging legs and the outturned portionsconstituting seats for contacting the sheet material, the engaging legscontacting the bars with substantially line contact, the coversotherwise being out of contact with the bars, the central curvedportions of said covers being put under strain when said covers areapplied to the bars thereby tending to urge said legs together, suchaction increasing the engagement of the covers with the bars.

2. Means for securing sheet material such as glass or the like toframing or glazing bars, including a spring sheet metal cover memberengageable with a framing bar with spring action for securing sheetmaterial to said bar, a framing bar having lateral grooves along thesides thereof, said cover having in the height thereof inwardly directedyportions constituting legs for engaging said grooves when a cover isapplied to a bar, said cover otherwise being out of contact with saidbar, the construction of the cover being such that the portionconnecting said legs is strained when the cover is in applied positionand the strain so imposed being eective to cause said legs to engagesaid grooves with spring action.

3. Means for securing sheet material such as glass or the like toframing or glazing bars, including a spring'sheet metal cover memberengageable with a framing bar with spring action for securing sheetmaterial to said bar, a framing bar having undercuts along thesidesthereof, said cover having in the height thereof inwardly andupwardly directed inturned portions constituting legs for engaging saidundercuts when said cover is applied to said bar, the portions of saidcover below said legs being outturned constituting seats for contactingsheet material, said last named portions being compressed when a coveris applied over a bar and against the sheet material, such compressiontending to increase the engagement of said legs with said undercuts.

4. Means for securing sheet material such as glass or the like toframing or glazing bars, including ay spring sheet metal cover memberengageable with a framing bar with spring action for securing sheetvmaterial to said bar, said'cover comprising a central connecting parthaving inturned portions alongthe sides thereof constituting legs forengaging a bar, a glazing bar having grooves along the sides thereofengageable by said legs, the connecting portion of said cover actingwith spring action to force said legs into engagement with said bargrooves when a cover is in applied position.

5. Means for securing sheet material such yas glass or the like toframing or glazing bars, including a spring sheet metal cover memberengageable with a framing bar with spring action for securing sheetmaterial to said bar, said cover having in the length thereof inwardlyand outwardly directed inturnedportions constituting legs, a framing barhaving undercut portions along its sides, the legs of said cover beingengageable with said undercuts when a cover is applied to a bar, theintermediate portion of said cover connecting said legs acting withspring action to squeeze said legs into engagement with said undercuts,portions of said cover below said legs being outturned constitutingseats for engaging sheet material, said last named portions beingcompressed when a cover is applied over a bar and against sheetmaterial, such compression tending to increase the spring engagement ofsaid legs with said undercuts.

RALPH W. EMERSON. S'I'IRLING H. HARPER

